Back-space mechanism



Sept. 18, 1928.

J. H. BARR BACK SPACE MECHANISM Filed Aug. 1. 1925 INVENTOR. JO/l/V a 5/71??? ATTORNEYS.

Patented Sept. 18, 1928.

N ET ED S1. AI P QF'F IfCIEL.

JOHN H. BARR, OI ITHACA, NEW YORIf ASSIGNOR TO. BARR-MORSE CDRPDBA'IION,.A CORPORATION OF NEW YORK.

BACK-SPACE MECHANISM.

Application filed August 1, 1925. Serial No. 475403;.

spacing mechanism for the carriage thereof.

An object of. the invention is to provide-i1n-- proved and simplified back 7 spacing mechanism which will ett'ectively back space the carriage in the usual mannerupon the opera,

tion of a key or controlling member: with which there will be no drag upon the carriage when the device is not in use; and which will be durable, etl'ective, simple and relatively inexpensive.

Various other objects and advantages will be apparent from the following description of one (-n'ibodimcnt of theinvention, and the novel 'teatures will be particularly pointed. out hereinafter in connection with the appended claims. I

In the accompanying:- drawing:

Fig. l is a sectional plan through a portion of a typewriting machine, and showing back spacer mechanism constructed in accordance with this invention, the tvpewrlter parts not imuiml atcly concerned with the invention beillif omitted for the purpose of clearness;

Fig. 2 is a sectional elevation through the same: and

Fig. 3 a side elevation oi the mounting for the improved pawl member forming. a part of the back spacer mechanism.

In the illustrated embodiment of the invention. the typewriter is provided with a rack 1 which is connected for operation con-- comitantlv with the carriage (not shown ,such as by a dir ct connection between the rack and The rack l provided with a plui tee? a :2 along the length of the same, by which it may be operated in the back spacinc operation, in a manner to be explained. 1 pair of bearing supports or elements 3 and t l to a suitaliile part of the frame one another, and a pawl member hav i a wire or rod-like body lidald and rotatahly meuntt d in the support- 3 and 4. The axes of the bearings of the supports which are coincident with the axis o'l' ihe member 5. are approximately parallel with the direction ot' travel of the rack 1. ()nc rnd (3 of the pawl 5 is bent angularly thereto and terminates in a pawl point or end '1" which is n wable into or out of engagement ot the rack 1 whenever the pawl I) is rotated in the bearing supports 3 i a somewhat similar manner, so

other end of the pawl 5 is bent as to form a crank; arm 8 dependingtheresfrom andentering a is pivotedzat l2 toza suitable part of th'e framep with the arm IOFcarryingthe cam'slob 9*ex tending approximatelycrosswise oft'he direc i0110fSlifliHglHOVQlllBDt of the=pawl.

The cam slot 9 extendspbliqu'ely to the axisotthe body of the pawl 5, as shown'inFlg. 1, so that when the bell: crank is-roeked upon its pivot 12,. itwill firstrock the pawl'about' its axis, and then shift it-lengthwi'se inthe bearing supports 3 and 4.- The bell-crank 11' may be disposedapproximatelv horizontally. and its other arm 13 is pivotally connected; by a pin 14' to one end of alink: lo extend'ing: forwardly of thermachine: The'fonward enclf ofthelink hasan= upturned eanlfi which ispivotally connectedwby asp-in 17 to a depending arm 18 of. a: key lever 19, the key lever'being hingedto a; sideiportion of the maohinwftameupon a horizontal axis-as at 20, and extending forwardlytherefa'om and terminating'ina key btlttOIliQL.

A leaf spring 22 is securedv at: one end to the frame of themachine in: any suitable manner, such as by'screws' 23-w-hielr pass therethrouglc and: alsoesecureone'of thebeer ing supports (3) to the frameas shown in Figslandl. The free end of the leaf spring rod 5 passes. The spring-22 is flexed to oneside of the normal position: in ordea -topass the body of the pawl 5:theretihrough, so that it will normally engage fzrictionally With thepawl 5 and yieldably restrict or oppose'both rotary and. sliding movements of the pawl. The free end. of the leaf springprefenably extends generally in the direction inwhich the pawl moves during the back spacing movement of the carriage so that whenthe pawl moves duringthe return or idle-section of its movement, the spring will tend to flex and offer less resistance to thetravel of'the pawl during the return stroke of the back space key.

In the operation of the backspacing mechanism which has been il'lustratedg whenever one desires to baclc'spacethe carriage thekey button 21 is depressed so as to carry the-key lever 19 fro1n the full. to the dotted positions in Fig. 2. During this movement the depend ing arm. 18 of the lever 19 will shift the link" cam slotrQ in one arm of a. belllerankleven 11: 'I hebell'erankdever l5 rearwardly into the dotted position shown in both Figs. 1 and 2, and in so doing will rock the bell crank 11 between the full line and dotted line positions shown particularly in Fig. 1. During the beginning of this movcment or the bell crank, the cam slot 9 thereof will act upon the crank arm 8 of the pawl and rock it in a rotary direction to carry the pawl point 7 into engagement with the teeth 2 of the rack 1. Thereupon when tin-the;- rotation of the pawl is stopped by the engagement of the pawl point with the rack, turt-her movement of the bell crank will shift the pawl endwi-se, that is, in a direction parallel with the travel of the rack l, and carry the rack 1 over a distance sufiicicnt to return the carriage one step of the escapement, that is, back space it one space.

The pawl point or angular end 7 is normally at such a distance from the support 2} that when the pawl 5 is moved endwise through a distance sutiicient to back space the carriage one space or slightly over, the pawl point or end 7 will engage with the sum port 3 and limit further movement of the pawl in the same direction. Since the pawl point or end 7 is in engagement with the carriage rack at that time, this limitation of the stroke of the pawl will ell'ectively prevent overlravel oi the carriage regardless of the force applied to the back space key. Thus, a violent stroke on the back space key cannot set the carriage back more than one step or space. While the bearing support 3 is suitable for limiting the endwise movement of the pawl 5, obviously any oi er limit step may be utilized instead, if desired. In Fig. 1, the dotted lines indicate the position of the back space pawl at the coniplction of the back space stroke, in which position the angular pawl end 7 abuts against the ear or support 3 while still in engagement with the carriage rack, and prevents even travel of the carriage.

'lhercupon when the key lever 19 is released, a suitable spring (not shown) whicl is connected to either the link 15 or lever 19, will return the lever to its full line position shown in Fig. At the beginning of this return movement, the bell crank 11 during the beginning oil its return movement will, by its cam slot 9, first rotate the pawl in the opposite direction to carry its pawl point '4' out of engagement with the rack l, and than upon continued movement of the bell crank. the pawl 5 will be shifted endwise into the full line initial position shown in Fig. l. 'ihe parts will then remain in this condition until the back spacing moement is again initial ii.

The spring 22 frictionally holds the pawl 5 in all angular and slidable positions, so that when it is moved out oi engagement from the rack, it will remain in that position until positively moved in a new hack spacing op eration. Since the spring 22 extends obliquely to the pawl body in a direction generally that in which the pawl body moves during the positive key stroke, that is, under the actuation ol' the operator, it will tend to lick slightly during the return stroke and oli'er le-s resistauce to the return ding movement ot the pawl when only the return spring is operating upon the key lever.

One of the supports, l, may have an extension in a position to act as a stop for the bell crank lever 11 at the end of its return movement, so to limit the movement of the bell crank lever under the actuation of the return spring 2% for returning the back spacing parts to normal position.

It will be observed that with thi improved back spacing mechanism, the travel of the carriage and con eeted rack l is unrestricted by the back spacing mechanism, and that the movement ol the pawl, during its engagement and disen: :emcnt iron'i the r ck. will be at fillllltzil, i ":s to the direction of travel of the rack. C etpiently a more accurate and. satistuctor back spacing occurs. will be observed that the parts are simple, durable. and emilv H554 llllllfitll liltl within the i such mechanisn'i.

We hat various changes in ch have been herein described and i hzs ted for the purpme of ex plaining the nature of the invention, may be made by those s illed in the art within the principle and scope ol the invention, er: pro :d in the appended cla inis.

I claim 1. In a t her lii-T?'\'..ilil( ed for sliding)- and r space l; connccti carriage, a pawl niozmo tary movement, a back 2 between said back space key and pawl or ating said pawl into enga cinent with th; eth oi said nieinher, and the pawl endwisc to carry t 'h during the one stroke :7- "i (ginning ott the pawl on. out or e 'i'rictionrlly or holding it t may be po moving ion while r yieldiniz'ljv he lJUFlllGll? which it connections.

1:1: chin a racl' movand having teeth e3- Jen -1th t; 1' the san'ie Enhstan the d of travel oi.

H-bcr mounted for roration. and iovement in a direction pzrallel to lln i M travel of said rack, aid ineni er havi. its pciwl point portion tuov: ble into at of engagement w th th 2 tcetli ra k when said member is rotated. l ke controlled means having lo: niotio crar connection to aid men. for opcratr r said member to back space rack and carriage, said means during the initial portion of the back spacing movement rotating the member to carry the pawl portion into engagement with the rack, and then antomatically operable upon the member to move it endwise during the remainder of this movement during the same stroke, said means being operable to rotate the member in a direction to carry its pawl portion out of engagement with the teeth during the initial part of the return movement, and then mov ing the member endwise to its initial position while free of the rack.

3. In a typewriting machine, a rack movable with the carriage and having teeth extending along the length of the same substantially parallel to the direction of travel of the carriage, a pawl member mounted tor rotation about an axis parallel to the direction of travel of said rack, and for sliding movement in a direction parallel to said axis, said member having its pawl point portion movable into or out of engagement vith the teeth of the rack when said member is rotated, and key controlled means having a crank connection to said member for operating said member to back space the rack and carriage, said means being operable during the initial portion of this back spacing movement to rotate the member and carry the pawl portion into engagement with th rack, and then move it endwise during the ren'iainder of this movement during the same stroke, said means being also operable to rotate the mem her in a direction to carry its pawl portion out of engagement with the teeth during the initial part of its return movement, and then to move the member endwise to its initial position while free of the rack, said means including a member having a cam slot ther in, and said member having a crank portion cn gaging in said slot, whereby upon movement of said member, the cam slot will rotate the crank portion to carry the pawl into or out of engagen'ient-with the rack during its initial movement in either direction and then move the member in a direction parallel to the travel of the carriage during the remainder of the same movement,

4. In a t vpcwriting machine, a carriage operated rack having teeth extending along the length of the same substantially parallel to the direction of travel of the carriage, a pawl member mounted for rotation, and also tor sliding movement in a direction parallel to the direction of travel of said rack, said member having a pawl portion movable into and out of engagement with the teeth of the rack when said member is rotated, said. memher also having a crank portion, and key controlled means connected to said crank portion for operating said member to back space the rack and carriage, said means being operable during the initial portion of this 1novement for rotating the member to carry the pawl portion into engagement with the rack,

operable upon the member to move it endwise during the remainder of this back spacing movement of the rack during the same stroke, and operable to rotate the member in a direction to carry its pawl portion out of engagement with the teeth during the initial part of the return stroke movement, and then moving the member endwise to its initial position while free of the rack, said means including a lever pivoted for oscillation on an axis extending transversely of the direction of travel of the carriage, said lever having in an arm thereof a cam portion with which the crank portion of said member cooperates, the cam surfaces of said cam portion extending obliquely to the axis of rotation of said member, whereby upon movement of said lever, the cam portion will rock said member to a limited extent before said lever imparts sliding movement to said memher.

5. In a typewriting machine, a rack movable with the carriage and having teeth extending along the same, supporting means having a bearing extending in a direction substantially parallel to the direction of travel of said rack, a pawl member sliding and rotating in said bearing and having a pawl arm movable into and out of engagement with the teeth of said rack when said pawl is rotated in said bearing, and key controlled means connected to said pawl tor imparting an initial rotary movement thereto, and then endwise movement thereto at each stroke, whereby the pawl arm will be carried into or out of engagement with the rack teeth at the beginning of each stroke and before movement axially of said bearing begins.

6. In a typewriting machine, a rack movable with the carriage and having teeth along the same, supporting means having a bearing extending in a direction substantially parallel to the direction of travel of said rack, a pawl member, formed of an elongated rod, sliding and rotating in said bearing and having two arms extending angular ly to the axis of said bearing, one angular arm of said pawl member having a pawl point movable into and out of engagement with the teeth of said rack when said pawl member is rotated in said bearing, and key controlled means connected to the other angular arm of said pawl member for imparting an initial rotary movement to said pawl member and then endwise movement thereto at each stroke, whereby the pawl point will be carried into or out of engagement with the rack teeth at the beginning of each stroke and before movement of the pawl member axiallv of said bearing begins, and a frictional device engaging with said pawl member for trictionally resisting both rotary and longitudinal movement thereof.

T. In a typewriting machine, a key lever pivoted upon a horizontal axis, a link con nected to said key lever and extending rearwardly therefrom, a bell crank pivoted upon a vertically extending axis and having one arm thereof connected to the rear end of said link, a rack movable with the carriage and having teeth extending along the same, a pawl rotatable into and out of engagement with the teeth of said rack, said pawl and other arm of said bell crank having a cam slot connection, whereby at the beginning of each operating movement of the bell crank, the pawl will be rotated into or out of engagement with the teeth of said rack before endwise movement is imparted thereto.

8. In a typewriting machine, a rack movable with the carriage and having teeth ex tending along the same, a pawl having a pawl point, means for supporting said pawl for rotation about an axis approxin'iately parallel to the direction of travel of said rack and permitting sliding movement of said pawl in a direction parallel with said rack, a leaf spring having an aperture through which the pawl passes with the spring pressing upon the pawl and frictionally res's in; the rotary and sliding movements thereof, and means including a member having a cam slot ant. crank connection to said pawl tor in'iparting both rotary and sliding movements to said pawl, whereby at the beginning of each movement oi said member the pawl will be first rotated into or out of engagement with said rack and then given a movement parallel to the rack.

9. In a typewriting machine, a rack connected for movement concomitantly with the carriage, a pawl mounted {or rotary movement into and out of engagement with the rack and for sliding movement with the rack, a leaf spring having an aperture through which the iawl extends, with the l-pllllfj; ex-

. ding obliquely to the xis oi rotation of said pawl, key controlled meal" connected to said pawl tor rotating the pawl into engagen'ient with the rac: during the initial operation of its back spacing st e and then shitting it end wise to back spa rack and carriage, the free end of said l-eat' spring extending in the direction or movement of the pawl during the back spacing movement, whereby the 1 'ictional resistance offered by the leat spring to the sliding moven'ient of the pawl will be a n'iininium during the return stroke.

10. In a typewriting machine, operated elen'ient having teeth a a carriage 1119, into a pawl mounted for rotary inovei'nent and out of eitqagementwith the teeth of s id element and also for slidin movement in the direction of travel of said eleniei'it, a member having a portion movable eneraliv in the direction of n'iovement of said clement, said portion having: a cam slot exlendi obliquely to saic dir ction of movement, said pawl having an arm in said slot and ope able by said member, whereby at each operation of said member the cam slot will first rotate the pawl to carry it into or out of engagement with the teeth of said element and then shift the pawl endwise, and means including a key for controlling the movements of said member.

11. In a typewriting machine, a carriage operated rack having teeth along the same in the direction of its movement, a rod disposed substantially parallel with the direction of travel of the rack and having its ends bent angularly thereto, means for supporting said rod for rotation and sliding movement, one angular end constituting a pawl arm, and a cam device connected to the other arm for rotating said rod to carry its pawl arm into or out of engagement with the rack teeth and then shifting it endwise during a continuance ot the same movement.

12. In a back spacing mechanism, a carriage, a rack connected to the carriage for movement concomitantly therewith, a rod disposed substantially parallel with the direction of travel of said rack and having a pawl extension, means for supporting said rod for rotation and sliding movement parallel to the axis of its rotation, and means for rotating said rod to carry its pawl portion into or out of engagei'nent with said rack and then shifting it endwise during a continuance of the same movement.

13. In a back spacing mechanism, a carriage, a rack connected to the earirage for movement concomitantly therewith, a rod disposed substantially parallel with the direction of travel of said rack and having a pawl extension, means for supporting said rod for rotation and sliding movement in the directions of travel of said rack, means for rotating said rod to carry its pawl portion into or out of engagement with said rack and then shifting it during a continuance of the same movement, and means for limiting endwise movement of said rod to prevent overthrow of said carriage.

14. In a hack space mechanism, a carriage, a member connected to the carriage for movement concomitantly therewith, a rod disposed substantially parallel with the direction of travel of said member, and having a pawl extension, means for supporting said rod for rotation and sliding movement parallel to the axis of its rotation, and means including cam mechanism connected to said rod for rotating it to carry its pawl extension into engagement with said member and then shifting it during a continuance of the same movement to back space the carriage.

15. In a back space mechanism, a carriage, a rack connected to said carriage for move ment concomitantly therewith. a rod disposed substantially parallel with the direction of travel of said rack and carrying a pawl extension movable into and out of engagement with said rack upon rotation of said rod about its longitudinal axis, cain means engaging with said rod for urging said rod in both rotary and longitudinal directions at the same time, and means cooperating with said rod for causing initial rotary motion until the pawl extension engages with said rack and then endwise movement of said member and rod to cause a back spacing of the carriage during a continuance of the same operation.

16. In a back spacing mechanism, a car-.

riage to be back-spaced, a rack movable with the carriage, a pawl mounted for rotation into and out of engagement with said rack and also shiftable in a direction parallel to its axis of rotation, to impart movement to said rack, and means connected to said pawl effective at each operation in either direction to first rotate the pawl into or out of engagement with the rack and then shift said pawl to a new position.

17. In a back spacing mechanism, a carriage to be back-spaced, a rack movable with the carriage, a pawl mounted for movementinto and out of engagement with said rack and also for movement in the direction of travel of the rack, and operating means con nected to said pawl, the connection between the pawl and means of itself being eITectivo at each operation of said means in either direction to move said pawl into or out of engagement wi h said rack and during further operation of said means to move said pawl in one of the directions of travel of said rack.

18. In a back spacing mechanism, a carriage to be back-spaced, a rack movable with the carriage, a pawl mounted for movement into and out of ei1*"; fen1ent with said rack and also for movement in the direction of travel of the rack, o 'ierating means connected to said pawl, the connection between the pawl and means of itself being effective at each operation of said means in either direction to move said pawl into or out of engagement with said rack and during further operation of said means to move said pawl in one of the directions of travel of said rack, and means for holding said pawl yieldingly in and out of engagement with said rack during travel of the pawl in the direction of travel of said rack.

In witness whereof, I hereunto subscribe my signature.

JOHN'H. BARR. 

